Let's get this math done. We have 647 and we're going to multiply it by 66. This is the same as taking 647 and adding it to itself 66 times.
Step 1: 0 + 647 = 647
Step 2: 647 + 647 = 1294
Step 3: 1294 + 647 = 1941
Step 4: 1941 + 647 = 2588
Step 5: 2588 + 647 = 3235
Step 6: 3235 + 647 = 3882
Step 7: 3882 + 647 = 4529
Step 8: 4529 + 647 = 5176
Step 9: 5176 + 647 = 5823
Step 10: 5823 + 647 = 6470
Step 11: 6470 + 647 = 7117
Step 12: 7117 + 647 = 7764
Step 13: 7764 + 647 = 8411
Step 14: 8411 + 647 = 9058
Step 15: 9058 + 647 = 9705
Step 16: 9705 + 647 = 10352
Step 17: 10352 + 647 = 10999
Step 18: 10999 + 647 = 11646
Step 19: 11646 + 647 = 12293
Step 20: 12293 + 647 = 12940
Step 21: 12940 + 647 = 13587
Step 22: 13587 + 647 = 14234
Step 23: 14234 + 647 = 14881
Step 24: 14881 + 647 = 15528
Step 25: 15528 + 647 = 16175
Step 26: 16175 + 647 = 16822
Step 27: 16822 + 647 = 17469
Step 28: 17469 + 647 = 18116
Step 29: 18116 + 647 = 18763
Step 30: 18763 + 647 = 19410
Step 31: 19410 + 647 = 20057
Step 32: 20057 + 647 = 20704
Step 33: 20704 + 647 = 21351
Step 34: 21351 + 647 = 21998
Step 35: 21998 + 647 = 22645
Step 36: 22645 + 647 = 23292
Step 37: 23292 + 647 = 23939
Step 38: 23939 + 647 = 24586
Step 39: 24586 + 647 = 25233
Step 40: 25233 + 647 = 25880
Step 41: 25880 + 647 = 26527
Step 42: 26527 + 647 = 27174
Step 43: 27174 + 647 = 27821
Step 44: 27821 + 647 = 28468
Step 45: 28468 + 647 = 29115
Step 46: 29115 + 647 = 29762
Step 47: 29762 + 647 = 30409
Step 48: 30409 + 647 = 31056
Step 49: 31056 + 647 = 31703
Step 50: 31703 + 647 = 32350
Step 51: 32350 + 647 = 32997
Step 52: 32997 + 647 = 33644
Step 53: 33644 + 647 = 34291
Step 54: 34291 + 647 = 34938
Step 55: 34938 + 647 = 35585
Step 56: 35585 + 647 = 36232
Step 57: 36232 + 647 = 36879
Step 58: 36879 + 647 = 37526
Step 59: 37526 + 647 = 38173
Step 60: 38173 + 647 = 38820
Step 61: 38820 + 647 = 39467
Step 62: 39467 + 647 = 40114
Step 63: 40114 + 647 = 40761
Step 64: 40761 + 647 = 41408
Step 65: 41408 + 647 = 42055
Step 66: 42055 + 647 = 42702

So, 647*66 = 42702